It's definitely not a fad. You will also find similar speakers with this tech labeled with "shorting rings" or "Farraday rings." As already touched upon, Dan Wiggins owns the "XBL" term. (As a side note, you guys remember the flashlights that were all the rage a couple years ago, the ones you shook up then used? Those are principally Farraday "motors" since the "coil" is shifted in the "magnetic gap" and can't leave it like a conventional coil can.) In layman's terms...have you ever bottomed out a sub or heard one bottom? It's not pleasant and not good for it. XBLs can't bottom out. Theoretically, you can beat the hell out of them with a ton of power without damage. They're not popular due to the XBL trademark, also because people would rather brag about putting 3000 watts into a 10. That's my opinion on the second part so like it or hate it, there it is Wait, what?